As　one　of　the　most　promising　conducting　polymers,　poly(3,4-ethylenedioxythiophene)　(PEDOT)　has　attracted　significant　interests　in　electrochemical　applications　such　as　energy　storage　and　electrochromism.　However,　the　intrinsic　PEDOT　having　a　dense　structure　usually　exhibits　unsatisfactory　electrochemical　performance　such　as　low　charge　storage　capacity　and　optical　modulation　behavior,　which　limits　their　applications　in　supercapacitors　and　electrochromic　devices.　In　this　case,　nanoengineering　provides　an　effective　strategy　to　improve　the　electrochemical　performance　by　optimizing　the　conjugated　structure　of　PEDOT.　Herein,　comprehensive　reviews　and　discussions　are　conducted　to　demonstrate　the　nanoengineering　of　PEDOT　for　boosting　the　electrochemical　applications.　The　advantages　and　shortcomings　of　PEDOT　are　discussed　firstly,　and　thus　introducing　the　necessary　of　nanoengineering　for　optimizing　the　electrochemical　performance.　Some　strategies　of　nanoengineering　are　summarized　according　to　the　classification　of　physical　and　chemical　methods.　Then,　the　latest　advances　and　progresses　are　reviewed　in　detail　concerning　the　applications　of　nanoengineered　PEDOT　in　supercapacitors　and　electrochromic　devices.　Finally,　some　challenges　and　prospects　are　proposed　to　show　the　further　development　of　nanoengineering　of　advanced　PEDOT　materials　and　devices.　We　anticipate　that　this　review　will　spark　new　ideas　for　the　construction　of　high-performance　PEDOT　towards　developing　advanced　electrochemical　devices.